Pseudomyogenic Hemangioendothelioma Research Articles

Pseudomyogenic Hemangioendothelioma Arising in the Maxillary Sinus, an Uncommon and Misdiagnosed Tumor: A Case Report.

Pseudomyogenic hemangioendothelioma (PMHE) is a rare vascular neoplasm with an intermediate to low-grade malignant potential. Only 5% of PMHEs occur in the head and neck. This tumor exhibits different histological patterns and mimics other vascular tumors, myoid tumors, or carcinomas. The distinction between these tumors can be a very challenging situation for pathologists. In this article, we report the first case, to our knowledge, of PMHE arising in the maxillary sinus, to highlight this uncommon entity and discuss differential diagnoses.

Molecularly Confirmed Pseudomyogenic Hemangioendothelioma with Unusual EGFL7::FOSB Fusion in the Head and Neck Region of an Older Patient

Pseudomyogenic hemangioendothelioma (PMHE), a rare vascular neoplasm, was first described in 1992 asa fibroma-like variant of epithelioid sarcoma, and would be termed as epithelioid sarcoma-like hemangioendothelioma a decade later due to its significant histologic overlap with epithelioid sarcoma and diffuse cytokeratin expression. PHME is currently defined as a distinct, potentially intermediate malignant, rarely metastasizing neoplasm with vascular/endothelial differentiation. It is characterized by young age (typically less than 40 years old), extremity location (approximately ~80%), and t(7:19) SERPINE1::FOSB fusion as the most common molecular alteration. Herein, we report a case of a 59-year-old male presenting with multifocal lesions, including in the right temporalis muscle, right frontoparietal calvarium, right pterygoid muscles, and right mandibular condyle. Histologic examination of the right temporal lesion revealed a multinodular biphasic lesion composed of sheets and fascicles of elongated spindle and epithelioid cells infiltrating into the adjacent skeletal muscle. Admixed abundant neutrophilic infiltration is noted; however, areas of necrosis, increased mitosis, nuclear atypia, or rhabdomyoblast-like cells are absent. Immunohistochemical (IHC) staining showed that the tumor cells were diffusely and strongly positive for FOSB, pan-cytokeratin (AE1/AE3), CD31, and ERG. Molecular testing demonstrated a t(9:19) EGFL7::FOSB fusion mRNA. This constellation of morphological, IHC and molecular findings was consistent with a diagnosis of PMHE. This is the first reported case of multifocal PMHE with EGFL7::FOSB fusion in the head and neck area of a patient aged more than 50 years old. Since the differential diagnoses for PMHE includes high-grade malignancies with aggressive clinical behavior, coupled with the rare reports of PMHE in the head and neck region, awareness of this tumor in the head and neck region will avoid the misdiagnosis and overtreatment of this entity.

Multifocal intraosseous pseudomyogenic (epithelioid sarcoma-like) hemangioendothelioma: A rare presentation of an uncommon tumor.

Pseudomyogenic hemangioendothelioma (PHE) is an uncommon mesenchymal neoplasm of intermediate malignant potential showing endothelial differentiation. Around 20 cases of primary osseous PHE have been reported to date. A 16-year-old boy presented with complaints of pain in his right leg. Imaging revealed multifocal intramedullary and cortical-based lytic lesions involving long and small bones. Microscopic examination revealed plump, spindled cells arranged in fascicles and admixed "epithelioid" and "rhabdoid" cells sans vasoformative areas. By immunohistochemistry, the lesional cells were reactive for AE1/AE3, CD31, Erg, Fli1, and SMA, while immunonegative for CD34, myogenin, and S100. Nuclear expression of the INI1/SMARCB1 protein was retained. PHE is a rare entity, more so as a primary osseous lesion; therefore, awareness of the presence of this entity in the bone is the key to making a diagnosis. We discuss its clinicopathological features, differential diagnosis, and an attempt a short review of the literature.

Cutaneous vascular tumors: an updated review

Cutaneous vascular tumors constitute a heterogeneous group of entities that share overlapping morphologic and immunohistochemical features, which can be diagnostically challenging for pathologists and dermatopathologists. Our understanding and knowledge of vascular neoplasms have improved over time, resulting in both a refinement of their classification by the International Society for the Study of Vascular Anomalies (ISSVA) and an improvement in the accurate diagnosis and clinical management of vascular neoplasms. This review article aims to summarize the updated clinical, histopathological, and immunohistochemical characteristics of cutaneous vascular tumors, as well as to highlight their associated genetic mutations. Such entities include infantile hemangioma, congenital hemangioma, tufted angioma, spindle cell hemangioma, epithelioid hemangioma, pyogenic granuloma, Kaposiform hemangioendothelioma, retiform hemangioendothelioma, pseudomyogenic hemangioendothelioma, Kaposi sarcoma, angiosarcoma, and epithelioid hemangioendothelioma.

Abstract IA005: On the use of stem cells to generate sarcomas in vitro models

Abstract Sarcomas are rare cancers arising in soft tissue and bone. They are difficult to diagnose and treat, with 38-48% mortality for this often young age group. It is now generally accepted that molecular changes in cancer open avenues for personalized medicine. However, to achieve this for sarcoma there are several challenges, as representative model systems are scarce. Moreover, sarcomas are heterogeneous and >70 sarcoma types are recognized. A simple dichotomy based on molecular pathways of simple versus complex genomics is often used as a conceptual framework. My group has used mesenchymal stem cells to generate a model for complex genome sarcomas such as osteosarcoma. Murine and canine mesenchymal stem cells (MSCs) can be used to model spontaneous malignant transformation towards sarcomas with complex genomics. These MSCs have an abnormal karyotype, many structural variants and point mutations at whole genome sequencing analysis, and form sarcomas (osteosarcoma, undifferentiated pleomorphic and spindle cell sarcoma) after injection into mice. Cross-species analysis reveals that p53 loss is an early event in sarcomagenesis, and MSCs with a knockout in Trp53 transform earlier compared to wild-type MSCs. In addition, loss of p16Ink4a is shown to be a driver of osteosarcomagenesis: the majority of spontaneously transformed murine MSCs has alterations in p15Ink4b, p16Ink4a, or p19Arf and knockout of these genes in MSCs results in accelerated transformation. Of interest, osteosarcoma cells with defective p16INK4A are sensitive to the CDK4/CDK6 inhibitor Palbociclib, suggesting that a subset of osteosarcoma patients with intact Rb, but defective p16 or overexpression of CDK4 and/or CDK6 (in total 20-23%) might benefit from CDK4/CDK6 inhibition. Bone and soft tissue tumors with a simple genome often carry chromosomal translocations. We have generated a model for pseudomyogenic hemangioendothelioma (PHE), a rare locally aggressive vascular tumor. PHE has a tumor-specific t(7;19)(q22;q13) translocation resulting in a SERPINE1-FOSB fusion. We used CRISPR/Cas9 to generate this fusion in induced pluripotent stem cells (hiPSCs), which were subsequently differentiated into ECs (hiPSC-ECs) to address this. Comparison of parental with PHE hiPSC-ECs shows invasive growth in mice after transplantation, and transcriptome analysis identifies PI3K-Akt and MAPK signaling pathways as possible therapeutic targets. The modified hiPSC-ECs thus recapitulate functional features of PHE and demonstrate how these stem cell based translocation models can be used to understand tumorigenic mechanisms and identify therapeutic targets. Citation Format: Judith V.M.G. Boveé. On the use of stem cells to generate sarcomas in vitro models [abstract]. In: Proceedings of the AACR Special Conference: Sarcomas; 2022 May 9-12; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(18_Suppl):Abstract nr IA005.

Primary pseudomyogenic hemangioendothelioma of bone:a clinicopathological analysis of two cases

目的： 探讨原发骨假肌源性血管内皮瘤（pseudomyogenic hemangioendothelioma，PHE）的临床病理特征、免疫表型、分子遗传学特征及鉴别诊断。 方法： 回顾性分析2例PHE的临床资料、组织病理学特征及免疫表型，并进行分子检测及复习相关文献。 结果： 例1，男，28岁，磁共振成像示腰5椎体破坏性病变。例2，女，56岁，肿瘤位于右手第2掌骨。镜下观察：瘤细胞由胖梭形至上皮样的细胞组成，胞质丰富，嗜伊红色，类似横纹肌母细胞；核染色质呈空泡状，核仁明显；另外部分区域可见片状出血、破骨细胞样巨细胞散在分布及反应性骨形成。免疫表型：瘤细胞表达FOSB、广谱细胞角蛋白、CD31、ERG和Fli1，但不表达CD34、上皮细胞膜抗原、结蛋白、平滑肌肌动蛋白和S-100蛋白，INIl显示无缺失。2例行FOSB荧光原位杂交检测均显示基因断裂信号。本组其中1例在短期内复发。 结论： 原发骨PHE是一种罕见的中间型软组织肿瘤，局部易复发，偶有转移，形态学上有上皮样肉瘤、上皮样血管内皮瘤及一些成骨性肿瘤的部分特点，诊断时必须结合免疫组织化学标记进行鉴别，必要时行分子检测。.

Total metabolic regression after everolimus in an adult patient with pseudomyogenic hemangioendothelioma

Total metabolic regression after everolimus in an adult patient with pseudomyogenic hemangioendothelioma

"Pseudotumors" in Dermatology.

In dermatology, “pseudo” is often used as a prefix for entities resembling another standard condition, either morphologically or histopathologically. Correspondingly, “pseudotumor” is a term encompassing dermatological conditions which are not true proliferations, but either have a clinical resemblance to a known tumor (e.g., Pseudokaposi's sarcoma is actually a non-neoplastic condition) or a histopathological resemblance to one (e.g., pseudo-myogenic hemangioendothelioma named due to a histopathological resemblance between myocytes and tumor cells). Often such a nomenclature can create confusion and unnecessary alarm for both the physicians and the patients. Through this article we attempt to summarise “pseudotumors” in dermatology and classify them into clinical and histopathological “pseudotumors”, so as to produce a ready reckoner for this confusing nomenclature.

S1‐Guideline Cutaneous Angiosarcomas – Update 2021

S1‐Guideline Cutaneous Angiosarcomas – Update 2021

Cutaneous Vascular Neoplasms of Uncertain Biological Behavior.

Simple SummaryCutaneous vascular neoplasms of uncertain biological behavior present a diagnostic and therapeutic challenge to physicians. The rarity of these lesions and the recent recognition of such entities suggests an extensive amount of knowledge remains lacking concerning effective treatments, accurate prognosis, and follow-up recommendations for patients with superficial vascular tumors. The objective of this manuscript is to compile a comprehensive summary of the current literature on neoplasms limited to the skin and of vascular origin that are currently categorized as indeterminate biological potential. By compiling numerous studies and summarizing the aggregate findings, this paper aims to offer providers a condensed yet detailed report of the entirety of what is known regarding these lesions. The information will aid physicians in the process of diagnosing, treating, prognosticating, and following up these rare tumors.Neoplasms of uncertain biological behavior present physicians with a genuine conundrum in practice. Cutaneous vascular neoplasms within this category are exceedingly rare, possessing significant gaps and uncertainty in many facets of clinical practice. Firstly, lesions were selected for review based on their categorization as indeterminate behavior, indicating the potential for local recurrence and rarely metastasize. After identification of the target lesions, a comprehensive review of the literature using national databases produced several landmark studies and case series regarding these neoplasms. Limiting the review to only cutaneous limited tumors narrowed the pool of studies; however, quite a large sum of papers remained. Examination of each paper yielded beneficial results on diagnosing, effective treatments, follow-up findings, and prognosis for each indeterminate lesion discussed. Overall, the literature search combined the molecular, histologic, immunohistochemical, surgical strategies to develop an up-to-date and comprehensive framework to guide physicians when encountering such lesions. The tumors reviewed include: kaposiform hemangioendothelioma, endovascular papillary angioendothelioma, pseudomyogenic hemangioendothelioma, retiform hemangioendothelioma, epithelioid hemangioendothelioma, and composite hemangioendothelioma.

Loss of expression of YAP1 C-terminus as an ancillary marker for epithelioid hemangioendothelioma variant with YAP1-TFE3 fusion and other YAP1-related vascular neoplasms

Epithelioid hemangioendothelioma (EHE) with YAP1-TFE3 fusion is a recently characterized distinctive variant of EHE that accounts for a small subset (<5%) of cases. It is composed of nests of epithelioid cells with voluminous pale cytoplasm and often shows focally vasoformative architecture. TFE3 immunohistochemistry (IHC) can be used to support the diagnosis; however, studies have questioned its specificity. Yes-associated protein 1 (YAP1), part of the Hippo signaling pathway, is expressed in normal endothelial cells, but becomes disrupted in EHE variant with YAP1-TFE3, such that only a small N-terminal region of YAP1 is expressed in the fusion protein. A recent study also reported YAP1 rearrangements in a subset of retiform and composite hemangioendotheliomas (RHE and CHE). In this study, we evaluated the diagnostic utility of an antibody directed against the C-terminus of YAP1 (YAP1-CT) for EHE with YAP1-TFE3, RHE, and CHE. In total, 78 tumors were included in the study: EHE variant with YAP1-TFE3 (n = 13), conventional (CAMTA1-positive) EHE (n = 20), pseudomyogenic hemangioendothelioma (n = 10), epithelioid hemangioma (n = 19), epithelioid angiosarcoma (n = 10), RHE (n = 4), and CHE (n = 2). IHC was performed using a rabbit monoclonal anti-YAP1 C-terminus antibody. EHE variant showed complete loss of YAP1-CT expression in 10 of 13 (77%) cases. All cases of RHE and CHE, with previously confirmed YAP1 rearrangements, also showed loss of YAP1-CT expression. Loss of YAP1-CT was seen in one conventional EHE (1/20; 5%). All other epithelioid vascular tumors showed retained YAP1-CT expression. Loss of expression of YAP1-CT appears to be associated with good sensitivity and specificity for EHE variant with YAP1-TFE3 fusion and may provide additional support along with TFE3 and CAMTA1 IHC in challenging cases. This marker may also be useful in the diagnosis of RHE and CHE.

Pseudomyogenic hemangioendothelioma: a challenging diagnosis of soft tissue pathology.

Pseudomyogenic hemangioendothelioma: a challenging diagnosis of soft tissue pathology.

Hemangioendothelioma Lumbar Spine and Ribs: Case Report

Background: Spine hemangioendothelioma is a rare low-grade vascular neoplasm that is characterized as intermediate between benign hemangioma and high-grade angiosarcoma, affecting 1 in 1,000,000 people worldwide. It has been described throughout the body with lung, liver, skin, bone and spine being the most frequent sites. Case presentation: A 31-year-old male, complained of mid and lower back pain for 2 years, which was on and off. 5 months ago pain increased after lifting heavy object, which affected his walking and sitting. No weight loss or night sweating. He came to Dr. Solaiman Fakeeh Hospital as second opinion regarding the Lumbar 1 (L1) tumor. The patient was diagnosed with pseudomyogenic hemangioendothelioma according to radiological images and histopathology report in other center. Conclusion: Through our experience in this case in the management of spine hemangioendothelioma tumor resection should be attempted whenever possible. Given the propensity of these lesions to recur, intralesional or subtotal resection

Unclassified mesenchymal sarcoma with NTRK1-KHDRBS1 gene fusion: a case report of long-term tumor-free survival with crizotinib treatment

BackgroundMesenchymal sarcomas are tumors that originate from mesenchymal tissue. Most mesenchymal sarcomas can be accurately classified, but some are unclassifiable in clinical practice. Molecular detection methods enable patients to benefit from molecular-targeted therapies for many cancers, including lung, breast, and bowel cancers. Further, even unclassified tumors can have therapeutic targets. NTRK gene fusions are sporadic genetic alterations that occur across tumor entities. If NTRK gene fusions are detected, TRK inhibitors can be used regardless of the tumor entity.Case presentationThis report describes a case with an unclassifiable mesenchymal sarcoma carrying a neurotrophic tyrosine receptor kinase NTRK1-KHDRBS1 gene fusion that was diagnosed and treated at multiple hospitals. Diagnostic work-up included pathological and immunohistochemical analysis, which excluded angiosarcoma, dendritic cell sarcoma, and pseudomyogenic hemangioendothelioma. The patient achieved a long-term survival without tumor relapse after treatment with crizotinib.ConclusionsThis case will be of significant interest to pathologists because, despite the tumor being unclassified, a molecular target was identified. Although the FDA does not currently approve crizotinib for treatment of patients harboring NTRK gene fusions, this case provides new insights for diagnosis and treatment of mesenchymal sarcomas with NTRK1 gene translocations. Similar to ALKomas, which can be successfully treated using NTRK molecular-targeted therapy, tumors with NTRK gene translocations can be classified as NTRKomas, even when they occur at different organ sites, and with varying histological morphologies, and immunophenotypes.

Vascular Tumor Recapitulated in Endothelial Cells from hiPSCs Engineered to Express the SERPINE1-FOSB Translocation

SummaryChromosomal translocations are prevalent among soft tissue tumors, including those of the vasculature such as pseudomyogenic hemangioendothelioma (PHE). PHE shows endothelial cell (EC) features and has a tumor-specific t(7;19)(q22;q13) SERPINE1-FOSB translocation, but is difficult to study as no primary tumor cell lines have yet been derived. Here, we engineer the PHE chromosomal translocation into human induced pluripotent stem cells (hiPSCs) using CRISPR/Cas9 and differentiate these into ECs (hiPSC-ECs) to address this. Comparison of parental with PHE hiPSC-ECs shows (1) elevated expression of FOSB, (2) higher proliferation and more tube formation but lower endothelial barrier function, (3) invasive growth and abnormal vessel formation in mice after transplantation, and (4) specific transcriptome alterations reflecting PHE and indicating PI3K-Akt and MAPK signaling pathways as possible therapeutic targets. The modified hiPSC-ECs thus recapitulate functional features of PHE and demonstrate how these translocation models can be used to understand tumorigenic mechanisms and identify therapeutic targets.

18473 Pseudomyogenic hemangioendothelioma: An aggressive case of a rare vascular tumor

A 19-year-old otherwise healthy man presented with new painful necrotic lesions on the left fifth toe and heel for four months. Symptoms began months after stepping on a foreign object and progressed rapidly despite multiple antibiotic courses. Imaging showed indeterminate findings of osteomyelitis. Noninvasive vascular studies revealed mild peroneal artery insufficiency. The patient started Aspirin and daily wound care without relief. He was then referred to Dermatology and biopsies were obtained. Histologic sections from both lesions showed a dense dermal proliferation of epitheliod to spindled cells with admixed neutrophils and eosinophils. Several immunohistochemical stains were performed: AE1/AE3(+), ERG(+), HHV8(−), Melan A(−), SOX-10(−), INI-1 (retained). Laboratory work-up was unremarkable including CBC, CMP, ESR, CRP, PT, PTT, ANA, ANCA, urinalysis, and blood cultures. The diagnosis of pseudomyogenic hemangioendothelioma was made and staging was initiated. Imaging revealed multiple tumor foci in the left metatarsal, tibia, groin, and lungs. Treatment consisted of toe amputation, wide local excision of the heel, and systemic everolimus. Pseudomyogenic hemangioendotheliomas are rare vascular tumors of intermediate malignant potential which classically present as multifocal painful nodules on the lower extremities of young males. While concurrent bone involvement can be seen in 20% of cases, distant metastases are exceedingly rare. Treatment is predominately surgical though recent detection of SERPINE1-FOSB gene fusions has prompted the use of mTOR inhibitors in unresectable tumors given their shared signaling pathways. This case represents an aggressive presentation of pseudomyogenic hemangioendothelioma with novel use of mTOR inhibitors as treatment.

The 2020 WHO Classification

The fifth edition of the World Health Organization Classification of Tumors of Soft Tissue and Bone was published in early 2020. The revisions reflect a consensus among an international expert editorial board composed of soft tissue and bone pathologists, geneticists, a medical oncologist, surgeon, and radiologist. The changes in the soft tissue tumor chapter notably include diverse, recently described tumor types (eg, atypical spindle cell/pleomorphic lipomatous tumor, angiofibroma of soft tissue, and CIC-rearranged sarcoma), new clinically significant prognostic information for a variety of existing entities (eg, dedifferentiated liposarcoma and solitary fibrous tumor), and a plethora of novel genetic alterations, some of practical diagnostic relevance (eg, NAB2-STAT6 in solitary fibrous tumor, FOSB rearrangements in epithelioid hemangioma and pseudomyogenic hemangioendothelioma, and SUZ12 or EED mutations in malignant peripheral nerve sheath tumor, leading to loss of H3K27 trimethylation). In this review, we highlight the major changes to the soft tissue chapter in the 2020 World Health Organization Classification, as well as the new chapter on undifferentiated small round cell sarcomas, with a focus on updates in diagnostic categories, prognostication, and novel markers. Recent discoveries in molecular genetics are also discussed, particularly those of immediate utility in differential diagnosis, including protein correlates detectable using immunohistochemistry.

Gallbladder Visualization in Peptide Receptor Radionuclide Therapy With 177Lu-DOTATATE

Gallbladder visualization represents a rare incidental finding when using somatostatin receptor-targeted SPECT radiopharmaceuticals such as In-octreotide. We present the case of a 30-year-old man with pseudomyogenic hemangioendothelioma who underwent Ga-DOTATATE PET/CT for restaging of metastatic disease and subsequent treatment with peptide receptor radionuclide therapy with Lu-DOTATATE. Posttherapeutic SPECT/CT, but not pretherapeutic or posttherapeutic PET/CT, showed gallbladder visualization, evidencing Lu-DOTATATE excretion into the bile. This case highlights that biliary Lu-DOTATATE excretion may represent a rare mimicker of hepatic metastases and emphasizes the role SPECT/CT for precise anatomical correlation to avoid misinterpretation.

Primary Vascular Tumors of Bone: A Monoinstitutional Morphologic and Molecular Analysis of 427 Cases With Emphasis on Epithelioid Variants.

Recent molecular discoveries have refined vascular bone tumor classification. To investigate the clinical relevance of these refinements, we reviewed all cases of primary vascular bone tumors treated at our Institute. On the basis of morphology, cases were assessed immunohistochemically and molecularly. A total of 427 cases of primary vascular tumor of bone with available follow-up and histologic material were retrieved and reclassified according to the most recent diagnostic criteria as follows: 289 hemangiomas, 38 epithelioid hemangiomas, 21 epithelioid hemangioendotheliomas, 2 retiform hemangioendotheliomas, 1 intraosseous papillary intralymphatic angioendothelioma, 24 pseudomyogenic hemangioendotheliomas, and 52 angiosarcomas (of these, 45 were epithelioid angiosarcomas and 7 spindle cell secondary angiosarcoma). Both epithelioid and classic hemangiomas behave as benign tumors with excellent prognosis. The distinction between cellular and conventional type of epithelioid hemangioma was not associated with a different clinical course. Conversely, epithelioid hemangioendothelioma exhibited a more aggressive clinical behavior than hemangioma, with higher rates of multifocality and distant spread. Immunohistochemical positivity for CAMTA1 or TFE3 did not have a prognostic implication. In epithelioid hemangioendothelioma, the presence of morphologic malignant features was associated with reduced disease-free (P=0.064) and overall survival (P=0.055). Pseudomyogenic hemangioendothelioma featured local aggressiveness in 5/24 patients exhibiting a clinical behavior closer to epithelioid hemangioma than epithelioid hemangioendothelioma. Last, 32/45 patients with epithelioid angiosarcoma died of disease with a median survival time of 10 months from diagnosis. In conclusion, the integration of morphologic, immunohistochemical, and molecular features allows a better stratification of primary vascular tumors of bone with significant prognostic and therapeutic implications.

Intercalary Reconstruction of the "Ultra-Critical Sized Bone Defect" by 3D-Printed Porous Prosthesis After Resection of Tibial Malignant Tumor.

PurposeThis study aimed to evaluate the early stability, limb function, and mechanical complications of 3D-printed porous prosthetic reconstruction for “ultra-critical sized bone defects” following intercalary tibial tumor resections.MethodsThis study defined an “ultra-critical sized bone defect” in the tibia when the length of segmental defect in the tibia was >15.0 cm or >60% of the full tibia and the length of the residual fragment in proximal or distal tibia was between 0.5 cm and 4.0 cm. Thus, five patients with “ultra-critical sized bone defects” following an intercalary tibial malignant tumor resection treated with 3D-printed porous prosthesis between June 2014 and June 2018 were retrospectively reviewed. Patient information, implants design and fabrication, surgical procedures, and early clinical outcome data were collected and evaluated.ResultsAmong the five patients, three were male and two were female, with an average age of 30.2 years. Pathological diagnoses were two osteosarcomas, one Ewing sarcoma, one pseudo-myogenic hemangioendothelioma, and one undifferentiated pleomorphic sarcoma . The average length of the bone defects following tumor resection was 22.8cm, and the average length of ultra-short residual bone was 2.65cm (range=0.6cm–3.8cm). The mean follow-up time was 27.6 months (range=14.0–62.0 months). Early biological fixation was achieved in all five patients. The average time of clinical osseointegration at the bone–porous interface was 3.2 months. All patients were reported to be pain free and have no limitations in their walking distance. No prosthetic mechanical complications were observed.ConclusionReconstruction of the “ultra-critical sized bone defect” after an intercalary tibial tumor resection using 3D-printed porous prosthesis achieved satisfactory overall early biological fixation and limb function. Excellent primary stability and the following rigid biological fixation were key factors for success. The outcomes of this study were supposed to support further clinical application and evaluation of 3D-printed porous prosthetic reconstruction for “ultra-critical sized bone defects” in the tibia.